package com.zhanghe.study.collections.map;

import java.util.Hashtable;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * hashTable
 * key和value不能为null
 */
public class TestHashTable {
    public static void main(String[] args) {
        Map map = new Hashtable();
        map.put(null,1);
        new LinkedHashMap<>();
    }

}
